Volcanoes and Plate Tectonics

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Vocabulary: Magma-molten-mixture of rock-forming substances, gases, and water from the mantle
Lava-when magma reaches the surface, it's called lava
Ring of Fire-a major volcanic belt, formed by the many volcanoes
Island Arc-resulting volcanoes make a string of islands
Hot Spot-an area where magma within the mantle melts

Outline

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What is a Volcano?

• Volcanoes
  • dangerous
    • awe-springing events
      • weak spots in crust
• Inside
  • has molten material and magma
• Magma
  • a molten mixture of rock-forming substances
    • gases
      • waters
        • from mantle
• lava
  • when magma reaches the surface

Location of Volcanoes

• many volcanoes
  • 600 active volcanoes on land
    • many more below sea
• Ring of Fire
  • a whole line of active volcanoes rims the pacific ocean
• Volcanic Belts
  • form along boundaries
    • huge pieces of crust diverge

Volcanoes at Diverging Plate Boundaries

• Volcanoes
  • form along mid-ocean ridge
    • marks a diverging plate boundary
• few places mid-ocean ridge rises above ocean surface
  • Iceland
    • Azores Island

Volcanoes at Converging Boundaries

• formed volcanoes
  • near plate boundaries
• occurrences of volcanoes
  • usually on land
• Island Arc
  • string of islands
    • formed by volcanoes

Hot Spot Volcanoes

• Hot spot
  • mantle from deep within the mantle melts
    • often lie in the middle of continental plates
• on ocean floor
  • gradually forms